Generally speaking, a vehicle seat assembly includes three fundamental components: (a) a frame to support the seat assembly and to mount it to a vehicle; (b) a foam cushion to cover the frame; and (c) trim material to cover the foam cushion and provide a durable surface for contact with a vehicle occupant. Typically, the foam cushion is made from an expandable foam material, such as polyurethane, and is molded to a predetermined shape during a molded process. The resulting molded cushion is typically a relatively light color such as white or yellow and has a grey scale rating of less than 30% grey (70% brightness) and in particular less than 20% grey (80% brightness). The resulting molded foam cushion also typically has a permeability of 5 to 30 ml/cm2/min.
The trim material may include any number of materials, such as cloth, polymers, or leather. Often, the selection of trim material is governed by the sale price of the vehicle. For example, leather trim material may be used for luxury vehicles while cloth and polymeric materials may be used for less expensive vehicles. The trim material is secured over the cushion to cover the cushion however, often times there remains certain areas where the trim material does not completely cover the cushion. In these uncovered areas, because of the contrast of color between the trim material and the cushion, there can be cushion show through that is noticeable to vehicle occupants.
These areas of show through can occur in any number of areas, depending on a variety of factors such as, the design of the cushion, the trim material, and the trim material attachment scheme. Certain examples of some relatively likely show through areas are at the trim close out, i.e., in the corners or edges of the cushion where the trim material is wrapped, or places where clips and/or seat belt components are present.
Depending upon the relative colors of the trim material and the cushion, cushion show through may be visible at these uncovered locations. These uncovered areas are especially noticeable when the trim material is relatively dark, such as those having a grey scale rating of more than 30% grey (70% brightness), and in particular greater than 50% grey (50% brightness), such as the case for blue, black and brown trim.
Prior art techniques to overcome this have been attempted. Two such examples are U.S. Publication No. 2007/0248789 and U.S. Publication No. 2009/0127912. The '789 publication employs the use of a fluid impermeable coating, which when applied to a foam cushion would provide only a superficial coating on the cushion surface and would be susceptible to degradation during prolonged use. The '912 publication discloses polyurethane coatings formed by reaction that also stays on top of the cushion.
Accordingly, there is a need to provide a vehicle seat assembly which has a seat cushion and trim material of relative contrast that inhibits cushion show through which can be manufactured easily and relatively economically and remain darkened with a durable coating over prolonged use. Moreover, even in situations with light colored trim, it may be desirable to provide a vehicle seat assembly that masks the appearance of the light colored foam cushion.